Dental coping and alloy useful in making the same



United States Patent 3,121,629 DENTAL CUPING AND ALLOY USEFUL IV MAKHNG THE SAME Herman Lionel Mann, Forest Hills, N .Y., assignor to Niraninm Corporation, Long Island City, N.Y., a corporation of New York No rawing. Filed July 13, 1960, Ser. No. 42,514 3 Claims. (Cl. 75-171) The present invention relates to dental copings, and it particularly relates to metal alloys useful in preparing such copings.

Dental copings are utilized as jackets or caps for prepared base members, which usually consist of teeth residues, Which copings are designed to carry a porcelain jacket crown or cap.

It is important that these copings have such coefficients of expansion and contraction with varying mouth temperatures and with taking of hot or cold liquids, fluids or foods into the mouth that they should not expand or contract so as to separate from or in any way become detached from the adhesive or cemented connection to the prepared stub or the porcelain or ceramic jacket or crown.

It is, therefore, among the primary objects of the present invention to provide a substantially unitary and integral junction between a porcelain or ceramic jacket or crown, an intermediate coping, and a prepared stub and the adhesive and cementing connections therebetween which will not be subject to rupture or weakening at normal mouth temperatures or at varying temperatures due to the reception of hot or cold foods or liquids in the mouth cavity.

Another object is to provide a coping construction and particularly an alloy therefor, which will be pressure resistive and will not tend to change in shape or size or tend to flatten or change its shape under normal biting or jaw pressures, which are of the order of many pounds per square inch.

It is, therefore, among the objects of the present invention to provide a resilient alloy for copings which will not tend to be pressed out of position, but which will better tend to be resilient and hold its shape or size under biting pressures.

Another feature that is important according to the present invention is the provision of a coping and an alloy therefor which, when oxidized or modified by chemical change within the mouth, will not tend to discolor the ceramic or porcelain cover.

It is, therefore among the further objects to provide such an alloy which will tend to resist oxidation or chemical change and which, when attacked by oxygen or mouth fluids, will tend to form an impervious or resistance surface layer which will protect the balance of the alloy or coping and which at the same time will be of the same color as the coping and not cause any discoloration.

A most important object of the present invention is to produce an alloy for the purpose above described, which when heated and cooled will expand uniformly with the porcelain jacket carried thereby or baked upon its surface so that there Will be no tendency of separation or cracking of such porcelain jacket.

Among the further objects of the present invention is the provision of an alloy which will melt at a reasonably elevated temperature without requiring temperatures above 2350 F. and which may be readily formed or shaped at temperatures of the order of 2200" F. to 2350' F.

Still further objects and advantages will appear in the more detailed description set forth below, it being understood, however, that this more detailed description is given by way of illustration and explanation only and not by way of limitation, since various changes therein may be made by those skilled in the art without departing from the scope and spirit of the present invention.

In accomplishing the above objects, it has been found most satisfactory to form this dental coping alloy from a combination of primarily chromium, nickel, and a metal of the platinum family together with relatively minor quantities of beryllium, silicon and molybdenum.

Desirably, the nickel should form at least of the alloy, and it may vary from 40% to of the alloy, with the chromium being used in the amount ranging from 40% to 50% of the nickel and desirably forming about 20% to 30% of the alloy.

The member of the platinum family should be present in a proportion of between 25% to 50% of the nickel and should be slightly less in amount than the chromium.

Preferably, the member of the platinum family might constitute as much as about 20% to 25% of the alloy, but the expense of such an alloy may be reduced by cobalt up to 15% of the alloy while the metal of the platinum family may then be reduced in content to below 10%.

The beryllium, silicon, molybdenum should be present in amounts ranging from about 1 to 4%.

1n the preferred form of the invention the beryllium, silicon and molybdenum metals may be present in about equal amounts, with the molybdenum being present in about twice the quantity of the beryllium or silicon.

Normally, the chromium appears to give the alloy corrosion resistance, while the nickel appears to give it hardness.

The cobalt and platinum member appears to give fluidity in casting, whereas the beryllium lowers the fusion point and causes less shrinkage.

As -a result of the inclusion of the beryllium, the fusion temperature may be controlled to be between 2200 P. to 2350 F.

The silicon appears to act as a degasifier.

The molybdenum appears to aid in the flowability, acts against oxidation and also acts as :a degasifying agent.

The platinum metal may be platinum itself or osmium, rhodium, palladium or ruthenium.

This platinum family metal aids in control of the fusion point, enhances the soldering quality, and aids in preventing oxidation as well as enhancing the flowing qualities.

The combination of the metals appears to give a resilient type of metal, which is most readily formed in a coping and which will readily adhere to the cement or adhesive connections inwardly to the stub and to the porcelain or ceramic packed outwardly to form a jacket.

The resilience, retention and coherence of the coping t0 the jacket and to the stub with varying mouth temperatures and various biting pressures appears to be due to the properties of the alloy as a whole, including the combination properties of the individual components, which [All in parts by weight] Metal Preferred Alternative 25 20 to 30 55 30 to 60 10 to 60 1 1 to 4 l 1 to 4 2 l to 4 Platinum Family Meta 21 1 to 30 Although cobalt may be omitted in the preferred composition, in the alternative composition where it is employed, the amount of the platinum family metal may be greatly reduced to less than 15% and in some instances, to less than 10%. Generally, this platinum family metal should range between 1 to 30% with the preferred portion of about 15 to 25% without the inclusion of cobalt and with a preferred range of 1 to 15 or 1 to 10 parts by weight when cobalt is included.

In such instances, the preferred amount of cobalt to be included will range between 5 to and desirably less than of the alloy.

In the preferred composition, the platium family metal may consist of two of the platinum metals such as platinum and palladium, or palladium and ruthenium, each in equal quantities.

Preferably, however, it consists of one member of the platinum family.

In some alloys, the beryllium, silicon and molybdenum may be omitted, but the platinum member, nickel and chromium should always be present in the proportions set forth above, such proportions being in parts by weight.

The above alloy is particularly useful in forming copings which fit over a prepared stub and carry a ceramic or porcelain jacket or crown baked directly to the said coping.

It is found that the particular alloy above forms an impervious oxidation coating which resists further penetration of the coping, and it is highly stable at temperatures ranging from 1400 F. to 2100 F. The alloy will melt at between 2250 F. to 2350" F.

A most unusual effect of the alloy resides in its durable and adhesive connection to the porcelain jacket.

The present invention differs quite remarkably from that set forth in Patent No. 2,761,778, dated September 4, 1956, in the inclusion of a member of the platinum family and in the omission of copper and also preferably cobalt, which appears to give the alloy altogether different properties and which enables use of the alloy, prepared as above, as particularly satisfactory in casting properties and enables formation into very thin copings of great strength and most effective adherent qualities, and offers much greater corrosion resistance to mouth acids than the composition set forth in Patent No. 2,761,778.

The alloy may also be used in crown and bridge work and for east crowns and dummy teeth as well as for copings for plastic teeth.

Although the amount of platinum family metal is of the order of about 20%, this same inclusion of platinum appears to give a noble metal quality to the entire coping alloy.

As many changes could be made in' the above dental coping and alloy useful in making the same, and many widely different embodiments of this invention could be made Without departure from the scope of the claims, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

Having now particularly described and ascertained the nature of the invention, and in what manner the same is to be performed, what is claimed is:

1. A non-separating coping alloy for application in com bination with porcelain jackets which will expand and contract with porcelain jackets at elevated temperatures at 2200 F. and 2250 F. forming a durable non-separating connection to the porcelain jacket consisting essentially of chromium, nickel, beryllium, silicon, molybdenum and a metal of the platinum family containing 40 to of nickel, 20 to 30% of chromium, 20 and 25% of the platinum family metal and the balance of the ingredients being present in the amounts of 1 to 4% said platinum family metal being selected from the group consisting of platinum, palladium and ruthenium.

2. A non-separating coping alloy for application in combination with porcelain jackets which will expand and contract with porcelain jackets at elevated temperatures at 2200 F. and 2250 F. forming a durable non-separating connection to the porcelain jacket consisting essen tially of 25 parts by weight of chromium, 55 parts by weight of nickel, 1 part by weight of beryllium, 1 part by weight of silicon, 2 parts by weight of molybdenum and 21 parts by weight of platinum family member said platinum family metal being selected from the group consisting of platinum, palladium and ruthenium.

3. A non-separating coping alloy for application in combination with porcelain jackets which will expand and contract with porcelain jackets at elevated temperatures at 2200 F. and 2250 F. forming a durable non-separating connection to the porcelain jacket consisting essentially of the following metals in parts by weight:

said platinum family metal being selected from the group consisting of platinum, palladium and ruthenium.

References Cited in the file of this patent UNITED STATES PATENTS Szabo Dec. 5, 1939 Tifft May 2, 1950 

1. A NON-SEPARATING COPING ALLOY FOR APPLICATION IN COMBINATION WITH PORCELAIN JACKETS WHICH WILL EXPAND AND CONTRACT WITH PORCELAIN JACKETS AT ELEVATED TEMPERATURES AT 2200*F. AND 2250*F. FORMING A DURABLE NON-SEPARATING CONNECTION TO THE PORCELAIN JACKET CONSISTING ESSENTIALLY OF CHROMIUM, NICKEL, BERYLLIUM, SILICON, MOLYBDENUM AND A METAL OF THE PLATINUM FAMILY CONTAINING 40 TO 55% OF NICKEL, 20 TO 30% OF CHROMIUM, 20 AND 25% OF THE PLATINUM FAMILY METAL AND THE BALANCE OF THE INGREDIENTS BEING PRESENT IN THE AMOUNTS OF 1 TO 4% SAID PLATINUM FAMILY METAL BEING SELECTED FROM THE GROUP CONSISTING OF PLATINUM, PALLADIUM AND RUTHENIUM. 